Ophthalmological conditions - Horner syndrome
Description
- Interruption of the oculosympathetic pathway -> ptosis + miosis +/- anhidrosis on the affected side
- *Horner syndrome is a localising sign, not a diagnosis. The task is always to find the lesion*
The three-neurone pathway
| Order | From -> to | Runs through |
|---|---|---|
| 1st (central) | Posterolateral hypothalamus -> ciliospinal centre of Budge | Brainstem, lateral medulla, cervical cord |
| 2nd (pre-ganglionic) | Ciliospinal centre of Budge (C8-T2) -> superior cervical ganglion | Ventral roots, over the lung apex, brachial plexus, thoracic outlet, along the subclavian |
| 3rd (post-ganglionic) | Superior cervical ganglion -> orbit | Along the internal carotid artery, cavernous sinus, with CN V1 (nasociliary) -> long ciliary nerves |
- Sudomotor fibres to the face follow the EXTERNAL carotid and leave at the bifurcation
- -> anhidrosis occurs with central and pre-ganglionic lesions, NOT post-ganglionic
- A post-ganglionic lesion may cause anhidrosis of a small medial forehead patch only
Epidemiology
- Uncommon; congenital ~1 in 6,000 births
- No age or sex predilection - the causes are what differ by age
- Young adult with pain: carotid dissection until proven otherwise
- Older smoker: Pancoast tumour
- Child: neuroblastoma (with heterochromia)
- Painful Horner syndrome = arterial dissection until excluded
Aetiopathogenesis
A. Central (1st order) - rarely isolated; look for company
- Lateral medullary (Wallenberg) syndrome - the classic
- Brainstem or hypothalamic stroke, tumour, demyelination (MS)
- Cervical or upper thoracic cord lesion - syringomyelia, tumour, trauma
- Almost always accompanied by other brainstem or long-tract signs
B. Pre-ganglionic (2nd order) - the most sinister group
- Pancoast (superior sulcus) tumour - apical lung cancer
- Brachial plexus injury - trauma, birth injury (Klumpke), radiation, tumour infiltration
- Thoracic outlet syndrome, cervical rib
- Thyroid or mediastinal mass, lymphadenopathy
- Iatrogenic - central line insertion, chest drain, thyroid/neck surgery, cardiothoracic surgery, interscalene block
- Aortic arch or subclavian aneurysm
C. Post-ganglionic (3rd order)
- Internal carotid artery dissection - the emergency
- Cavernous sinus lesion - tumour, thrombosis, aneurysm, inflammation (Tolosa-Hunt)
- Middle cranial fossa or skull base tumour, nasopharyngeal carcinoma
- Cluster headache and other trigeminal autonomic cephalalgias; migraine
- Otitis media, herpes zoster, carotid endarterectomy
D. Congenital
- Birth trauma, neuroblastoma
- Iris heterochromia (lighter iris on the affected side) - sympathetic innervation is needed for melanocyte pigmentation in infancy
Diagnosis
Clinical signs
- Ptosis - from paralysis of Muller's muscle (superior tarsal, sympathetically innervated)
- Mild (1-2 mm) - the levator palpebrae superioris is unaffected (that is CN III)
- Affects BOTH upper and lower lids -> "upside-down ptosis"/reverse ptosis of the lower lid -> apparent enophthalmos
- Miosis with dilation lag - the pupil dilates slowly in darkness from loss of active dilator tone
- Anisocoria is greater in the DARK (vs a third nerve palsy or Adie pupil, where it is greater in the light)
- Reaction to light and accommodation is normal
- Anhidrosis - central and pre-ganglionic lesions only; its absence localises to post-ganglionic
- Conjunctival injection, transient ocular hypotony, facial flushing (harlequin sign)
- Iris heterochromia if congenital or acquired before ~2 years
Localising the lesion clinically - look for the company it keeps
| Site | Accompanying signs |
|---|---|
| Brainstem | Diplopia, ataxia, vertigo, dysphagia, crossed sensory loss, weakness |
| Spinal cord | Weakness, long-tract signs, a sensory level, sphincter involvement |
| Brachial plexus / apex | Small hand muscle wasting, T1 weakness, arm and shoulder pain, clubbing, supraclavicular node |
| Cavernous sinus | CN V1 sensory loss with diplopia (III, IV, VI) and NO brainstem signs |
| Carotid dissection | Ipsilateral neck/face/periorbital pain, pulsatile tinnitus, amaurosis fugax, dysgeusia, lower cranial nerve palsy |
Pharmacological confirmation
- Apraclonidine 0.5-1% - the test of choice (cocaine is obsolete in Australian practice)
- Weak alpha-1 agonist; denervation supersensitivity -> the Horner pupil dilates and the ptosis reverses; the normal pupil constricts slightly -> reversal of anisocoria
- *Requires 24 h - and usually 3-7 days - for supersensitivity to develop. A negative test in the acute setting does NOT exclude Horner syndrome*
- Avoid in infants <6 months - CNS depression
- Hydroxyamphetamine 1% localises pre- vs post-ganglionic (dilates if post-ganglionic fibres are intact) - largely unavailable, and imaging has superseded it
Imaging - do not try to localise before imaging
- New Horner syndrome in an adult = image the entire sympathetic pathway: hypothalamus -> brainstem -> cervical cord -> lung apex/thoracic outlet -> carotid -> cavernous sinus
- CT angiography or MR angiography of head and neck, extending from the circle of Willis down to at least the carina/aortic arch
- Add T1 fat-saturated sequences on MRA neck - markedly increases detection of intramural haematoma in dissection
- A chest X-ray is a reasonable first screen for an apical mass but is no longer sufficient - CT/MRI is now first-line
- MRI brain and cervical cord if central signs
- Urgency: painful, acute, or with neurological symptoms -> image today. Isolated, long-standing and stable -> can be worked up semi-urgently
- Congenital/paediatric: urinary catecholamines (HVA/VMA) + MRI neck, chest and abdomen for neuroblastoma
- Old photographs are genuinely useful - a long-standing Horner needs no work-up
Management
Management is management of the cause. The Horner syndrome itself needs nothing.
A. Exclude and treat the emergencies
| Cause | Action |
|---|---|
| Carotid artery dissection | Antithrombotic therapy - antiplatelet or anticoagulation (equivalent stroke prevention in CADISS and TREAT-CAD); usually 3-6 months, then reimage. Stroke risk is highest in the first days - treat immediately. Avoid neck manipulation and heavy lifting; consider stenting only for recurrent ischaemia |
| Stroke / lateral medullary syndrome | Acute stroke pathway - thrombolysis/thrombectomy assessment, then secondary prevention; swallow assessment before anything oral |
| Pancoast tumour | Urgent CT chest and tissue diagnosis (EBUS/CT-guided biopsy), staging PET; concurrent chemoradiation then surgery in resectable disease |
| Neuroblastoma (child) | Urgent paediatric oncology referral |
| Cavernous sinus thrombosis | Antibiotics + anticoagulation; urgent imaging |
| Cluster headache | High-flow oxygen and subcutaneous sumatriptan acutely; verapamil for prevention |
| Spinal cord lesion | Urgent MRI, neurosurgical referral |
B. Symptomatic
- Ptosis is mild and rarely needs treatment; apraclonidine drops or Muller muscle conjunctival resection if cosmetically significant
- Reassure - vision, pupil reaction and accommodation are normal
- No treatment for anhidrosis or heterochromia
C. If no cause is found
- ~30-40% of isolated Horner syndrome remains idiopathic after full imaging
- Document, photograph, and review; repeat imaging if new symptoms emerge
- Do not label as idiopathic without adequate vascular and apical imaging
Associations
- Carotid and vertebral artery dissection - spontaneous, or after trauma, neck manipulation, coughing; fibromuscular dysplasia, Ehlers-Danlos type IV, Marfan
- Apical lung cancer (Pancoast) - with T1 wasting, arm pain, rib destruction
- Lateral medullary (Wallenberg) syndrome - vertebral or PICA territory
- Syringomyelia and Chiari malformation - with cape-distribution dissociated sensory loss
- Cluster headache and other trigeminal autonomic cephalalgias (Horner is transient and ipsilateral to the pain)
- Neuroblastoma in children; birth trauma with Klumpke palsy
- Multiple sclerosis, neurosyphilis, herpes zoster
- Iatrogenic - internal jugular line, chest drain, thyroid and carotid surgery, interscalene brachial plexus block, epidural in labour
- Raeder paratrigeminal syndrome - Horner + trigeminal pain with preserved facial sweating
Natural history & complications
- The syndrome itself is benign and non-progressive; the prognosis is entirely that of the underlying cause
- Carotid dissection: most recanalise over 3-6 months; stroke risk concentrated in the first 2 weeks; the Horner syndrome is often permanent
- Pancoast tumour: 5-year survival ~30-50% with trimodality therapy in resectable disease; much worse if unresectable
- Cluster headache: the Horner may become permanent after repeated bouts
- Congenital: heterochromia is permanent
Complications
- Those of the cause - stroke (dissection, brainstem infarct), brachial plexopathy and respiratory failure (apical tumour), cord compression
- Cosmetic ptosis and asymmetry
- Missed diagnosis - the main hazard is dismissing an isolated Horner in a young person with neck pain
Monitor
- Serial neurological examination and repeat vascular imaging at 3-6 months in dissection
- Photographic documentation for later comparison
- If initially idiopathic, re-examine and re-image if any new sign appears - especially arm pain, hand wasting, or weight loss
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